There are two components in KRAD which can convert BOs into XML via XStream. One is the BusinessObjectSerializerServiceImpl The other is the XmlObjectSerializerServiceImpl.
Unfortunately, they configure the XStream object differently. And, despite the name, the BO service is not always used for BOs. In fact, in most cases, it delegates to the latter. This means that some of the configuration, most noticably these lines:
are not being used.
I do not know if this is a problem or not. But, it seems that, if BOs start using the AutoPopulatingList class, they may not be handled properly.